This invention relates to a gripper member control device for bookbinding machines, as used for transferring books, magazines, and the like.
Known heretofore in the field of bookbinding machines are apparata whereon books, magazines, brochures, and the like are formed progressively. Such apparata are arranged to perform various processing steps on a work line along which the books or the like being formed are caused to move. The book translation movement is provided by chain drives and members specially constructed for their intended functions.
One of the operations carried out on such book-binding machines or apparata is that of gripping the books or the like being formed and taking them from a substantially upright position to a position whereat they are laid onto a conveyor belt preparatory to stacking together the books in groups.
Said transfer movement is effected, on advanced design machines, by means of specially provided gripper members which adjust automatically for the book thickness, and during the transfer movement apply the required force to improve the adhesion of the cover or flap on the book.
Such gripper members, which are provided in large numbers, and driven along a closed loop path adjacent the book and the like formation line, derive their work motion from a drive which utilizes that same pulling action which moves the members in question along a closed loop path.
In practice, it is contemplated that each gripper member be translated by means of drive chains along fixed runways having fixed racks positioned therealong. Arranged to mesh with these racks is a gear wheel standing out of each gripper member and forming said drive. The gear wheel is forced to rotate about its axis by the movement of the related gripper member and on account of the fixed position of the racks, and the rotation is transmitted, for example, to a worm driving a gear made rigid with the shaft around which each gripper member is arranged to rock.
As a whole, this control device is particularly advantageous by virtue of its being simple, accurate in operation, and implying no arrangements of specific drive elements at the gripper members.
However, this control device implies the solution of the problem of how to cause each drive or gear wheel to correctly mesh with a fixed rack as the gear wheel first contacts the rack. It should be considered, in fact, that each gear wheel is driven at a relatively high speed along with its corresponding gripper member, and that during these movements, small angular oscillations take place naturally which make the angular position of each gear wheel at the time of meshing with a fixed rack a practically random one. And it may be appreciated that where the gear wheel position is not the correct one for meshing with the rack, there may be created at the time of engaging each gear wheel with one rack a condition of strong impact which may result in various failures and in all cases considerably shorten the life of the control device as indicated.